Parallel-stranded oligonucleotide duplexes containing 5-methylisocytosine-guanine and isoguanine-cytosine base pairs
作者:Frank Seela、Yang He、Changfu Wei
DOI:10.1016/s0040-4020(99)00511-6
日期:1999.7
Parallel-stranded oligonucleotides containing 5-methylisocytosine-guanine and/or isoguanine-cytosine base pairs were prepared. The coupling efficiency was higher than 99% when the phosphoramidites of 2′-deoxy-5-methylisocytidine (2a) and of 2′-deoxyisoguanosine (3) were employed in solid-phase synthesis. The glycosylic bond of 2′-deoxy-5-methylisocytidine (1a) is stabilized against acid in the case
制备包含5-甲基异胞嘧啶-鸟嘌呤和/或异鸟嘌呤-胞嘧啶碱基对的平行链寡核苷酸。当2'-脱氧-5-甲基异胞苷(2a)和2'-脱氧异鸟苷(3)的亚磷酰胺用于固相合成时,偶联效率高于99%。在am衍生物4a,b的情况下,2'-脱氧-5-甲基异胞苷(1a)的糖基键对酸稳定。长时间暴露于氨中会发生脱嘧啶作用。使用the准分子荧光明确确定了平行链(ps)双链体的取向。反平行(aps)双链体d(A 12)•d(T 12)(25•26当两个中心的腺嘌呤-胸腺嘧啶碱基对被异鸟嘌呤-胞嘧啶对取代时,变为平行方向。发现包含5-甲基异胞嘧啶-鸟嘌呤碱基对的ps-双链体的热稳定性显着低于具有异鸟嘌呤-胞嘧啶对的ps-双链体的热稳定性。根据CD光谱,与aps对应物相比,ps-DNA-DNA或DNA-RNA杂种在二级结构上表现出差异。